When this occurs, you de-select whatever you had selected and select the city. You can find lots of info in the bottom left corner.
That's great! Oh, wait. Where does it show unrest? Or what I am paying in maintenance? Or how many materials the city has? It shows Guildar, Growth, Research and Production, and not as part of the active UI element. I don't think the details button in the HUD is clickable with the dialog up. (I could be wrong) I am just asking for a Details button in the level up UI window so you can check before you make your choice.